For many TV fans, NBC's long-running "Law & Order" franchise conjures up images of perverts and murderers, wisecracking detectives and self-important district attorneys trying to put the bad guys in jail.

Flip to USA or TNT, where the original "L&O" series and its spinoffs are featured regularly, and you might catch them and other stand-up comedians and comic actors cast as some of television's creepiest characters.

And more are coming. On Sunday, Whoopi Goldberg turned up as a villainous foster mother in a new prime-time episode of "Law & Order: Criminal Intent." And on "Law & Order: Special Victims Unit" this fall, Jerry Lewis will play a homeless man accused of murder.

"There's a certain sparkle these guys bring," said Fred Berner, one of the executive producers of "Criminal Intent."

"We like to think of our criminals and perps being as equally entertaining as our stars, and you have a relatively short period of time to make the audience familiar with the characters," Berner explained. "So if they have some sparkle and you can bury their personality a little bit in the darkness of one of our characters, you bring them alive in a unique way."

"Saturday Night Live" has proven a fertile casting ground, as has "The Daily Show."

Rene Balcer, another executive producer of "Criminal Intent," says that as actors, comedians can often tap into the underlying anger and resentment that not only fuel great comedy but also help illustrate what makes criminals tick.

"They're willing to push the envelope a lot more than a lot of other actors" in front of the camera, he said. "If you look at famous comedians, whether it's (John) Belushi or (Chris) Farley or any of those guys, they had no qualms about making fools of themselves, or doing anything."

On television, Garofalo has spent much of the last year playing Louise Thornton, a Democratic campaign strategist on "The West Wing." Bob Newhart played an architect contemplating suicide on "ER" in 2003. And police work has been comedian Richard Belzer's on-screen job for 14 years, as Det. John Munch on "Homicide: Life on the Street" and now as the same character on "Law & Order: SVU."

At "Law & Order," producers say, a specific actor will sometimes come to mind for a script; other times their agents contact the shows expressing interest.

Filling the shoes of a well-scripted character on a single episode doesn't require the time commitment of a movie project. And as much as they enjoy getting laughs, comedians are often eager to try a creative challenge.

Lewis agreed to appear on "SVU" at the urging of Belzer, a longtime friend. "He's a huge fan of the show, and I said, 'You should come on,'" Belzer said. The producers "figured out a story that he liked."

Hammond, a stand-up best known for his Al Gore and Bill Clinton impersonations on "Saturday Night Live," has appeared on "SVU" and "Criminal Intent," most recently as a bully who sexually harasses an employee.

"I feel like a clown in the sense that I am," he said. "I wear a lot of paint on my face and fake noses and ears. So to think that even for a second that I could act alongside these great actors is thrilling."

It can also be intimidating. There he was in a tense scene, Hammond recalled, with Vincent D'Onofrio (Det. Robert Goren) getting in his face like he always does with the bad guys, trying to pin a rap on him.

In the 2004 episode, "The Saint," writers brought Colbert to "Criminal Intent" as a tightly wound and somewhat pretentious handwriting expert who swindles a Catholic foundation and blows up a grandmother with an explosive device.

But not every comic necessarily plays the bad guy.

"SVU's" executive producer, Neal Baer, says he likes to mix it up. He's cast comedian Jim Gaffigan as a clown who preys on children, Bernhard as a defense attorney and Black as a crass radio host.

While it might seem enticing to cast a comedian for the name draw, Baer said, "We always go for acting ability. We do it because it's going against type."

Belzer sees some of his comic stage personality in the role of Munch, who's given to dark trench coats, a rebellious streak and cynical-yet-wry observations about people.

He still occasionally goes out on the road to do stand-up comedy, but he said he's content right where he is, working on a hit television show. "This is the best role I could possibly have."